Background: The etiology of malabsorption syndrome (MAS) may differ in different geographical regions. Limited data are available on the etiological spectrum of MAS among Indian adults. Methods: Ninety-nine consecutive adult patients with MAS (urine d-xylose or =7 g/24 h) were evaluated for cause of MAS using standard criteria. Past medical records were examined to know the nature of treatment received. Results: The etiology of MAS was: tropical sprue 39, celiac disease 9, Crohn's disease 9, giardiasis 8, small intestinal bacterial overgrowth in absence of another cause of MAS 8, panhypogammaglobulinemia 2 (one with strongyloidiasis), intestinal lymphangiectasia 1, intestinal tuberculosis 4, idiopathic 15, acquired immunodeficiency syndrome 2, and amyloidosis 2. Twenty-eight patients had received anti-tubercular treatment earlier. Conclusions: Tropical sprue, celiac disease and Crohn's disease are common causes of MAS in Indian adults. Inappropriate anti-tubercular treatment is common in them and needs to be discouraged.